* Europe's third-busiest air traffic corridors quieter
* Recession hits overflights to southern, eastern Europe
* Drop in plane movements outpaces lower passenger numbers
By Tim Hepher
PARIS, March 18 (Reuters) - The number of commercial planes flying over France is down 12 percent compared with a year ago in a further sign of economic weakness hitting European airlines and manufacturers, according to French air traffic controllers. France is home to Europe's biggest cargo traffic hub and the world's leading tourist destination, as well as handling over a million overflights a year that do not show up in local data.
Europe's largest airline, Air France-KLM, reported a 2.9 percent drop in its global passenger traffic in February and Paris airports operator ADP said passenger numbers there fell 8.1 percent.
But the drop in economic activity appears wider when not only a slump in cargo, but also a decline in the number of flights over French territory, are included, controllers said.
"We are now seeing a drop of 8 percent in flight movements in our region compared to a year ago and 12 percent nationally," Jean-Michel Goupil, who heads Europe's third-largest air traffic control centre situated near Paris, told Reuters.
The figures are based on data starting from Jan. 1 to this week and compare with a fall of 1.8 percent in 2008 as a whole.
"The damage has all come in the past three months," he said.
Air traffic control data is not usually made public rapidly but gives a broad snapshot of the airborne economy and is instantly available to its users.
Sitting in one of five regional French air traffic control centres, Goupil's 500 controllers organise the skies around Paris airport Charles de Gaulle, Europe's busiest in terms of both flight movements and cargo traffic, as well as nearby Orly.
The centre handles some 1.3 million flights a year, behind Maastricht in the Netherlands and the no.1 centre London, which handle some 1.5 and 2 million flights a year respectively.
OVERFLIGHTS
Data is gathered in real-time showing the number of aircraft being herded along air traffic corridors, held in airport arrival stacks or passing through "shelves" of controlled airspace at various altitudes anywhere in the country.
Controllers monitor large computer screens showing composite radar plots and are assigned sectors like "Southern Departures".
At around 1600 GMT on a sunny afternoon as France was bracing for a day of air and transport strikes, a central screen showed that a total of 399 planes were using controlled airspace in France. "That's quiet," the shift manager explained.
On a peak day the Paris centre alone can handle around 4,400 flights spread over 24 hours, mostly arriving or departing the capital. At Aix-en-Provence in southern France, a similar centre is busier with traffic to or from southern Europe, helping to account for a sharper drop in movements nationwide.
Overflights are more sensitive to volatile economic trends because they are less influenced by capacity constraints at Orly, the second Paris airport, which flattens the trends in data, the centre's deputy director Michel Mathias said.
Airlines are cutting capacity to make up for a steep drop in demand, though this does not in all cases mean fewer flights as carriers can switch to smaller planes.
Also weighing on traffic, Air France-KLM said cargo traffic fell 18.5 percent on a comparable basis in February.
The head of Air France-KLM told Reuters last month that normal patterns have been so disrupted by industry destocking in Europe, caused by the financial crisis, that Europe was temporarily exporting more to China than it imported by air.
One positive impact of the crisis on the Paris centre?
"It is easier to organise the shifts. There are fewer planes so we can bundle sectors together," Mathias said.